A Fairfax County nonprofit group has pulled together enough landowners to create a special tax district, the missing piece in the public-funding plan for 23 miles of Metro stations from Reston to Dulles International Airport and beyond, officials said Friday.

"This will be a major economic boon for the county and the corridor, and it will provide a much-needed transit option for that part of the county," said Sharon Bulova (D), chairman of the county Board of Supervisors.

The Western Alliance for Rail to Dulles, a nonprofit group made up of Fairfax landowners, has recruited a majority of affected landowners to create the tax district, which would pay for $330 million in capital funding for the project. Fairfax would pitch in $90 million. Thirty-five landowners, about 57 percent of those affected, signed the group's petition.

"This is a time-consuming process to get these signatures," said Jeffrey J. Fairfield, vice president of the alliance and a lawyer representing Launders Charitable Trust, which owns 15 acres in the area. "I think in the final analysis, many of these landowners came to the conclusion that while times are hard now, it would have been unthinkable without rail."

The petition needs to be approved by the Herndon Town Council and the Fairfax Board of Supervisors. Bulova, who has made rail to Dulles a priority, said she expects the tax district to be in place by the end of the year, which would allow cash reserves to be built up to pay down bonds once they are issued. Tax rates would start at 5 cents per $100 of assessed value next year and increase to 20 cents in 2013.

U.S. Rep. Gerald E. Connolly (D-Va.), former chairman of the Fairfax board, said the announcement was critical in ensuring that Metro extends service through Fairfax and into Loudoun County.

Connolly said that although the economic climate might have delayed creation of the tax district, an announcement last month by Science Applications International Corp. that it would move its headquarters to Tysons Corner is a sign of the region's financial health.

"The case had to be made to the business community that this was a decision that was out of self-interest for the future," he said. "You do not want to be stranded without rail service, like Georgetown."